Treatment of fibers, threads, and the like, derived from protein materials



Patented Aug. 25, 1942 TREATMENT or means, THREADS, AND

Team, naarvan mom PROTEIN MA- TERIALS Theodoor Koch, Oosterbeek, Netherlands, assign or to American Enka Corporation, Enka, N. 0., a corporation of Delaware no Drawing. Application October 9,1939, Serial No. 298,715. In Germany November 9, 1938 9 Claims. (01. 1ss4) The present invention relates to the manufacture of synthetic filamentous materials and more particularly to .the treatment of fibers or threads produced from protein solutions such ascasein.

In order to increase the water resistance of. protein fibers, it is a common expedient'to subject the fibers to formaldehyde baths.- However, the fibers so treated are by no means sufliciently resistant to hot aqueous solutions such as dye baths. In a weakly acidic dye bath, which is normally employed for dyeing natural wool, protein fibers will lose weight and assume a rubberlike structure and upon drying stick together and become extremely brittles Moreover, during the drying period the fibers will shrink as much as 30% or 40% and sometimes even more. It is also known to treat protein fibers with baths containing both formaldehyde and an acid, but then the specific procedure is followed of subsequently, immediately washing the fibers acid-free and finally using a neutral after-hardening bath. In this case, also, the fibers are acted on unfavorably in hot dye baths.

In accordance with the broad invention, it has been determined that casein fibers, having improved physical and chemical characteristics particularly with respect to water resistance, can be produced if, after the normal treatment with a formaldehyde solution, the fibers are subjected to a bath containing an aldehyde and an acid and then prior to washing, are given drying treatments including heating in order-to partially or completely dehydrate th fibers.

In conducting the process, baths may be employed to which an acid and an aldehyde per se are added, or compounds may be utilized that subsequently give rise to, or form acids oraldehydes or both. For example, compounds ofthe type triammonium phosphate (NHi') 31 04, zinc chloride ZNCh and sodium ethyl sulphate CzHsNaSOi will give an acid reaction in the bath and on subsequent heating or drying; hexa- CHaClQSQCl will, on heating, give oi! formaldehyde as well as acids. 7 1

Several diflerent types of acids maybe used or produced in orderto improve the quality of the finished product, but usually the strong acids.

such as hydrochloric and sulphuric are preferred.

maintained rather high, e.'g., a pH of 5 will give noticeable improvements, ranging up to a pH of 2 whereinafter the casein fiber has been treated and dried, it has high resistance to hot acid dye baths. Moreover, the shrinkage is reduced to at,

least 6%. The invention contemplates using even higher concentrations without damaging the fibers, for example, 10% HCl or H2SO4. In order to obtain the best results, the fibers, afterthey have been'dried in acid condition, are heated to a temperature of approximately 100 C.; alternatively the fibers may be dried in acid condition andthereafter heated in an aldehyde vapor.

As previously stated, the resulting components should be acids and aldehydes, and if by using this process or any modifications thereof, the in- During heating, if it is desired to accelerate I the dehydration, compounds suchas butanol may be used to form azeotropic mixtures; or the materiais may be distilled with organic com unds that are immiscible with water, for example toluol.

Compounds which dehydrate or have a tanning effect on the fiber can be used to advantage in the acid, aldehyde bath, in this connection the sulphates of aluminum, chromium and sodium may be employed and aromatic sulphonic acids or condensation products of aromatic sulphonic acids with formaldehyde.

The following examples serve to more fully illustrate the invention:

Example I Fibers produced from an alkaline casein solution are extruded and spun through an acid coagulating bath and thereupon partially hardened in a neutral or vfeakly acidic bath containing 10% formalin and finally washed and dried. The casein fibers are then immersed for one hour in a bath containing parts of water, 10 parts of formaldehyde and 5 parts of HCl. Upon 'removal from the said bath the fluid is extracted from the casein fibers by'pressing or centrifug-' .ing, and dried at a temperature of 50 C. The

fibers areagain heated for one-half hour at C. and finally washed acid-free and dried. The casein fibers treated in accordance with this pro- Normally, the acid concentrationjof the bath is 55 cedure, were found to bewater-resistant when dyeing in acid dyes at 95 C. and the shrinkage was reduced below 6% Example II Casein fibers hardened in the normal way with formalin are immersed air-dried in a solution which contains 95 parts of butanol and parts of methylene sulphate. After an hour, the fibers are centrifuged and the excess butanol removed by distillation and the fibers then heated for two hours at 100 C. Finally they are washed acidfree, finished and dried. Treated in this manner, the fibers are substantially resistant to thermolysis.

Example III Normally hardened casein fibersare treated with a 5% H01 solution without washing, centrituged and dried. Thereupon they are exposed in a closed container to the action of dry formaldehyde vapor for a period of one hour at a temperature of 110 C. The fibers are then further treated in accordance with Example 2.

Example IV Casein fibers preliminarily hardened in the usual manner are subjected to treatment for one hour in a bath containing 83 parts of water, 4 parts of anhydrous aluminium sulphate, 5 parts of formaldehyde and 8 parts of concentrated sulphuric acid. After centrifuging, the fibers are dried and heated for one-half hour at 115 C. They are finally washed acid-free and finished. These fibers are completely resistant to thermolysis.

While the invention in its preferred embodiments has been described in connection with casein fibers, it is obvious that it' is applicable to various types of synthetic fibers of protein origin.

What is claimed is:

1. A process for increasing the water-resistance of protein fibers and the like, that have been previously hardened in an aldehyde bath in the usual manner which comprises subjecting the fibers to the action of an aldehyde and acid bath and thereupon drying and heating the fibers without previous washing.

2. A process for increasing the water-resistance of protein fibers and the like, that have been previously hardened in an aldehyde bath in the usual manner which comprises immersing the fibers in a bath containing an aldehyde and acid, and thereupon drying. and heating the fibers without previous washing.

3. A process for increasing the water-resistance of protein fibers and the like. that have been previously hardened in an aldehyde bath in the usual manner which comprises immersing the fibers in a bath, which bath contains compounds that will form aldehydes and acids, and thereupon drying and heating the fibers without previous washing.

4. A process according to claim 1 wherein the said bath contains a tanning agent.

5. A process according to claim 1 wherein the heating takes place in a medium containing an aldehyde vapor.

6. A process according to claim 1 wherein the drying and heating takes place in the presence of compounds forming azeotropic mixtures with water, which compounds have a boiling point above 100 C.

7. A process for increasing the water-resistance of fibers obtained from alkaline casein solutions which comprises hardening th fibers with a formaldehyde solution, washing and drying, subjecting the fibers to a formaldehyde bath that has an acid concentrationbetween pH 5 and pH 2, extracting the liquid and drying for a timeat a temperature approximately 50 C. and then heating for about one-half hour at 110 C., and finally washing the fibers acid-free and drying.

8. A process for increasing the water-resistance of fibers produced from alkaline casein solutions which comprises preliminarily hardening the fibers in a formalin bath, treating the fibers for at least an hour in an aqueous bath containing aluminum sulphate, formaldehyde and sulphuric acid, subjecting the fibers to a twostage drying operation, the second stage being conducted at a temperature above C., finally washing the fibers acid-free and drying.

9. A process for increasing the water resistance of protein fibers and the like, that have been previously hardened in an aldehyde bath in the usual manner which comprises immersing the fibers in a bath containing substances of the class consisting of aldehydes and acids, and compounds that form aldehydes and acids, and thereupon drying and heating the fibers without previously washing.

THEODOOR KOCH. 

